Metal-organic framework membranes for wastewater treatment and water regeneration

Chitosan is a cationic polymer obtained by deacetylation of chitin, found abundantly in crustacean, insect, arthropod exoskeletons, and molluscs. The process of obtaining chitin by the chemical extraction method comprises the steps of deproteinization, demineralization, and discoloration. To obtain chitosan, the deacetylation of chitin is necessary. These polymers can also be extracted through the biological extraction method involving the use of microorganisms. Chitosan has biodegradable and biocompatible properties, being applied in the pharmaceutical, cosmetic, food, biomedical, chemical, and textile industries. Chitosan and its derivatives may be used in the form of gels, beads, membranes, films, and sponges, depending on their application. Polymer blending can also be performed to improve the mechanical properties of the bioproduct. This review aims to provide the latest information on existing methods for chitin and chitosan recovery from marine waste as well as their applications.

Seafood Waste as Attractive Source of Chitin and Chitosan Production and Their Applications.

Electrospinning superhydrophobic–superoleophilic fibrous PVDF membranes for high-efficiency water–oil separation

Fabrication strategies, sensing modes and analytical applications of ratiometric electrochemical biosensors

Nanomaterial-doped conducting polymers represent a unique class of composite materials that synergizes the advantageous features of nanomaterials and organic conductors, and they have been used in many applications such as electrochemical sensors and energy storage devices. Conducting polymers can be controllably synthesized from various monomers, and during the polymerization process, different nanomaterials offering unique physical and chemical properties can be doped into the formed conducting polymer composites. In this review, we focus on recent advances in electrochemical sensors and biosensors based on conducting polymers doped with various nanomaterials, including carbon nanomaterials, metal or metal oxide nanoparticles and quantum dots. Approaches to fabrication of films of these materials are described and sensing applications for different targets are summarized.

Nanomaterial-doped conducting polymers for electrochemical sensors and biosensors

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

Superhydrophobic poly(vinylidene fluoride) PVDF-SiO2 composite membranes with different % of SiO2 contents were prepared by electrospinning. The surface morphologies of the membranes are characterized by using scanning electron microscopy. The nanofibers in the membranes were stacked in layers to produce fully interconnected pores that resulted in high porosity. The incorporation of SiO2 into the nanofiber membrane improved the ionic conductivity from 0.2428 × 10-4Scm-1 to 7.731 × 10-4Scm-1 at room temperature. The surface roughness of the membranes increased with increasing the SiO2 content, while the average diameter of nanofibers was rarely affected. Superhydrophobic PVDF membrane with a contact angle larger than 136° was prepared by the electrospinning of the SiO2 functionalized PVDF. The surface composition of the membranes is analyzed by using FTIR and the contact angles and water drops on the surface of the membrane are measured. The contact angle experimental results of PVDF-SiO2 composite membranes showed an improvement of hydrophobicity with % of nano SiO2.

https://file.scirp.org/pdf/SNL_2013041109433706.pdf

Preparation of PVDF/SiO 2 Composite Nanofiber Membrane Using Electrospinning for Polymer Electrolyte Analysis

In this study, chitosan nanoparticles (CH-NPs) were synthesized using Penaeus semisulcatus shrimp shells and characterized using UV–Vis and FT-IR spectroscopy, as well as XRD and HR-TEM analyses. CH-NPs were investigated for growth inhibition properties against selected species of bacterial and fungal pathogens, showing performances higher or comparable over positive controls, respectively. Furthermore, CH-NPs were tested on three important mosquito vectors, achieving LC50 from 12.27 to 14.62 µg/ml. In addition, CH-NPs were evaluated using in vitro plant tissue culture by rooting gel method, to enhance the vegetative growth of the medicinal plant species Sphaeranthus indicus. With the simple technique presented here, large-scale industrial production of CH-NPs is possible. They can be used to develop pesticides highly effective against mosquito vectors of high medical and veterinary importance, as well as for plant tissue culture and food packaging applications.

Single Step Fabrication of Chitosan Nanocrystals Using Penaeus semisulcatus: Potential as New Insecticides, Antimicrobials and Plant Growth Promoters

In this paper, we report a facile low-cost synthesis of the chitin and chitosan-based hybrid nanocomposites for supercapacitors. The chitosan and chitin based hybrid composites functional group analysis, structural, optical and morphological properties were characterized using FTIR spectroscopy, Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy (SEM), respectively. Specific capacitance values of hybrid composites were calculated using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge analysis. The hybrid composites asymmetric supercapacitor performance was perceived in the range of −0.2 to 1.0 V. The specific capacitance value was achieved at 542.63 F g−1 at current density value of 0.1 A g−1 for CH-GO-ZnO/PANI hybrid composites. The prepared hybrid nanocomposites exhibit good supercapacitive performance and long-term cycle stability. These results demonstrate the potential of the CH-GO-ZnO/PANI hybrid nanocomposites as a high-performance supercapacitors.

Chitin and Chitosan Based Hybrid Nanocomposites for Super Capacitor Applications.

Amperometric polymerization of aniline was carried out in the presence of TritonX-100. Entrapment of tyrosinase (polyphenol oxidase, PPO) onto polyaniline in the presence of TritonX-100 with glutaraldehyde as a cross-linking agent results in a biosensor for polyphenols. Catechol is taken as a model compound. Cyclic voltammetric studies reveal the electroactivity of catechol on the developed biosensor. HR-SEM shows the surface morphology of polyaniline prepared in the presence of TritonX-100 (PANI(T)) and polyphenol oxidase entrapped polyaniline in the presence of TritonX-100 (PANI(T)–PPO). The optimum reaction conditions to construct the polyaniline, tyrosinase based catechol biosensor are studied. The linear concentration range is from 5 × 10−7 to 1.65 × 10−4 mol dm−3, with a Michealis–Menten constant Km = 85.44 μmol dm−3 and an activation energy of 41.74 kJ mol−1. It retains 65% of the original activity after 25 days, which is much higher than that of other biosensors. With a lower quantity of enzyme loading, better response, sensitivity, shelf life and higher stability are observed. The developed biosensor was used to quantify catechol in green tea samples and the results were compared with those from HPLC.

V. Sethuraman

Papers

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

Preparation of PVDF/SiO 2 Composite Nanofiber Membrane Using Electrospinning for Polymer Electrolyte Analysis

Single Step Fabrication of Chitosan Nanocrystals Using Penaeus semisulcatus: Potential as New Insecticides, Antimicrobials and Plant Growth Promoters

Chitin and Chitosan Based Hybrid Nanocomposites for Super Capacitor Applications.

Fabrication of an efficient polyaniline–polyphenol oxidase based biosensor for catechol